Lift truck mast assembly



C. J. BRINTON July 30, 1968 LIFT TRUCK MAST ASSEMBLY Filed Nov. 25, 1966 3 Sheets-Sheet 1 CALEB J. BRINTON ATTORNEYS y 30, 1968 c. J. BRINTON LIFT TRUCK MAST ASSEMBLY 3 Sheets-Sheet 2 Filed Nov. 25, 1966 CALEB J. BRINTON F f BY /?4J- 6? ATTORNEYS C. J. BRINTON July 30, 1968 LIFT TRUCK MAST ASSEMBLY 3 Sheets-Sheet 5 Filed Nov. 25, 1965 0 m1 Mm R B J- B E L A C A'iTORNEYS United States Patent 3,394,778 LIFT TRUCK MAST ASSEMBLY Caleb J. Brinton, Holland, Pa., assignor to Eaton Yale & Towne Inc., Cleveland, Ohio, a corporation of Ohio Filed Nov. 25, 1966, Ser. No. 596,922 7 Claims. (Cl. 187-9) ABSTRACT OF THE DISCLOSURE Relates to a mast for a lift truck having a flange member at the upper end of the fixed uprights and at least one ram fixed at its upper end to the flange with the ram piston bearing against a similar flange connected to the upper end of the secondary upright. One end of a chain is fixed to the flange member to counteract the thrust of the ram as it lifts a third upright via a sprocket attached to the upper end of the secondary upright.

This invention relates to an industrial or lift truck having extendible uprights, a lifting load carriage and hydraulic ram means for elevating the uprights and load carriage. The lift truck of the present invention utilizes a series of telescoping uprights, more particularly three or more sets of telescoping uprights, which, when extended, permit high lifting of a load while allowing the truck to have relatively low overall height when the uprights are lowered.

In truck-s of this type it is desirable that the load carriage have substantial free lift, i.e., vertical movement of the load carriage without extension of the uprights. This allows the load carriage to be lifted without increasing the overall height of the truck, thereby permitting operation of the loaded truck in areas of low overhead.

It is also desirable that the uprights and load carriage can be fully extended to their uppermost position with the shortest possible lift ram. Prior lift truck designs known in the art have utilized lift ram arrangements having relatively long rams and requiring involved mounting schemes for the ram and uprights. Furthermore, it is also desirable to arrange the load carriage mounting and ram lifting means so that the driver will have a better view in a forward direction.

In the past, related lift truck mechanisms have utilized relatively complicated arrangements for mounting the lift ram On one of the associated uprights and chain arrangements for effecting the lifting of the uprights upon extension of the ram piston.

It is the main object of the present invention to provide a compact, simple lift truck design utilizing mast upright sections, disposed in extensible telescopic relation to each other, having a lift ram mounted on one of said mast sections in a unique arrangement for extending the mast sections of said lift truck assembly.

Another prime object of the present invention is to provide a new and improved lift truck assembly wherein the assembly includes a load supporting carriage movably mounted on one of said mast sections and separably movable along substantially the whole length of its supporting mast section to thus obtain a full free lift of said load supporting carriage without any extension of the mast upright sections.

Another main object of the present invention is to provide an improved lift truck mechanism having vertically disposed telescopic mast uprights with one of said uprights being fixed and the others mounted for relative longitudinal movement and actuated by lifting chains and a lift ram means mounted on a flange integral with said fixed upright in a manner such that the reaction force 3,394,778 Patented July 30, 1968 of said ram means acting on said flange is in part balanced by a lifting chain attached to the flange.

Another object of the present invention is to provide a mast assembly which is designed to afford the operator a clear view through the mast assembly and a full unobstructed view around other portions of the vehicle.

Another important object of the present invention is to provide a new and novel lift truck device having vertically disposed mast uprights and a hydraulic ram fixed to a first upright at its upper end, a second upright of said lift truck assembly having integral means proximate said ram piston for engagement thereby, said ram being so mounted that its piston moves but a relatively short distance to engagement with said second upright integral member effecting lifting of said second upright.

Still other objects and advantages of the mast assembly of the present invention will be realized by one skilled in the art to which it pertains and upon reference to the following disclosure thereof, the inventive concepts of the same being illustrated in several preferred embodiments and the accompanying drawings forming a part of this specimen, and wherein:

FIGURE 1 is a perspective view of a lift truck constructed in accordance with the present invention, showing the uprights and load carriage in the lowered position;

FIGURE 2 is a perspective view similar to that of FIG- URE 1 but showing the uprights and load carriage in an elevated position;

FIGURE 3 is a diagrammatic side elevational view of the mast assembly of the present invention showing the mast sections thereof removed from their nested assembly and disposed one in front of the other to more clearly illustrate the inner-connection between the same;

FIGURE 4 is -a partial side elevational view showing details of the mast assembly of the present invention with the uprights and load carriage in an elevated position;

FIGURE 5 is a sectional view taken on line 5-5 of FIGURE 4;

FIGURE 6 is a sectional view taken on line 6-6 of FIGURE 4;

FIGURE 7 is a perspective view showing details of the ram cylinder mounting and chain attachment on the fixed upright of the mast assembly of the present invention.

The mast assembly of the present invention is designed for use with an industrial or lift truck generally indicated as T in FIGURES 1 and 2. The details of the truck as the transmission, engine, body design, etc., are not a part of the present invention and therefore, are not described in detail.

The mast assembly of the present invention is mounted in a generally vertical plane on the front end of the truck T as shown in FIGURES 1 and 2. The rear of the mast assembly of the present invention is provided with suitable bearing blocks 5 and bearing caps 6 (see FIGURE 4) by which the mast assembly is mounted for limited swinging movement relative to the front axle housing of the lift truck; such a mounting arrangement of the mast assembly to provide forward and reverse tilting of the mast assembly is well-known in the lift truck art. The primary upright 10 of the mast assembly is fixedly attached to the bearing blocks 5 as seen in FIGURE 4, and thus, mounted to the front end of the truck T.

As best seen in FIGURES 5 and 6, the primary upright assembly has a pair of channel uprights 10 arranged with the channeled portions facing in an inward direction toward the center of the assembly. The primary uprights are joined at their bottom ends by a plate member 11 and at their upper ends by a U-shaped flange member 12. The plate'member 11 and the U-shaped flange member 12 provide lateral support to the primary uprights 10 although the flange member 12 has a more important function to be described hereinbelow.

Mounted within the opposing pair of open face prim-ary uprights 10 are nested pairs of second or secondary uprights 13, third or tertiary uprights 14, and fourth or quad uprights 15 as best seen in FIGURES 5 and 6. The second, third, and fourth pairs of uprights are I-beam shaped in cross-section and disposed in parallel spaced relation and rigidly connected together at their respective ends by bracing members. As seen in FIGURES 5 and 6, mast sections 13, 14 and 15 are equipped with rollers 13, 14, and 15' respectively, that ride in the channel of the adjacent I-beam sections.

Each of the mast sections are substantially identical in length and arranged to be telescoped within one another for a compact structure. As before mentioned, the channel shaped primary member is mounted to the truck T. The second or secondary upright 13 is slightly smaller in its dimension than channel shaped member 10 and nested within the primary section and disposed in slightly inwardly spaced relation thereto by means of roller 13' so as to be freely slidable longitudinally therealong. In a like manner, upright members 14 and 15 are arranged in step-like fashion from secondary member 13 and tertiary member 14 respectively, and disposed for relative longitudinal slidable movement by rollers 14' and 15. The stepped arrangement of sections 13, 14 and 15 permits a substantial area of vision through the center of the mast structure for the operator.

A load oanriage generally indicated as 21 is supported on the fourth or quad section 15, the carriage having spaced pairs of rollers 22 (see FIGURE 4) which are disposed so as to be rollably engageable with the inwardly facing section of quad mast 15 to advance the load carriage 21 t-herealong.

A hydraulic ram 23 is provided for raising or lowering the load carriage 2-1 within its supporting mast section 15 between its fully raised position as shown in FIGURE 2 and its lowermost position as shown in FIGURE 1. The ram cylinder is mounted between the pair of the I- beam members comprising quad section 15 by welding or other suitable means of attachment. The ram cylinder is so mounted on a cross support member 26 which extends between the pairs of upright members comprising quad section 15 in a manner so that the ram piston faces upwardly. As seen in FIGURE 4, a transverse shaft 27 is provided on the upper end of ram piston for mounting thereon a load sheave or roller 28, the particular type mounting of the transfer shaft 27 and sheave 28 on the upper end of the ram piston 25 to be utilized in the present invention is thoroughly described in Patent 2,979,162 issued on April 11, 1961, to the common assignee. The particular mounting of the before-described shaft and sheave on the upper end of the piston ram does not comprise a part of the present invention and thus, will not be described in detail herein. A pair of flexible members such as link chains 32 have one end anchored at 30 to a plate carried by quad section 15, and pass over the sheave 28, extending downwardly and being securely anchored at 31 to the load carriage 21.

With the before-described load carriage assembly, it is seen that upon applying hydraulic fluid to the primary cylinder 24 of ram 23, the ram piston 25 will be forced upwardly so as to raise the sheave or roller 28 therewith which is effective to pull the load carriage 21 through the chains 32. The velocity at which the load carriage 21 moves upwardly along its supporting mast section 15 is substantially twice that of the velocity of the ram piston 25 as it moves out of its cylinder. The length of the primary ram 25 is proportioned so that when the ram piston 25 is fully extended the sheave or roller 28 and the load carriage 21 will be positioned at the upper end of mast section 15.

The before-described movement of the load carriage 21 is accomplished with the mast assembly in its collapsed condition, as seen in FIGURE 1, and is referred to in the art as the full free lift of the load carriage. Such free lift is highly desirable to permit operation of the lift truck in areas of low overhead in carrying loads in some intermediate position along the length of quad mast 15 without any extension of the mast assembly from its collapsed height.

The major uplifting achieved by a lift truck utilizing the present invention is through the extendible uprights and secondary ram arrangement to be now described. A pair of secondary hydraulic rams are disposed rearwardly of the primary ram 23 and in such manner to have their cylinder upper ends mounted to the before-described flange member 12 which interconnects the upper ends of primary uprights 10. The secondary ram cylinders 42 :are provided with a flange 41 at their upper ends which is connected to the underside of the primary upright flange member 12 by bolt means. Such a mounting of the ram cylinders at their upper end permits their lower ends 43 to be unsupported which is important for reasons to be set forth hereinbelow.

In prior art arrangements for mounting such a secondary hydraulic ram for effecting lifting of the extendible upright sections as in the present invention, it has been customary to mount the hydraulic ram in a vertical position, usually in the center area of the truck, with the lower end of the ram resting on a stationary part of the truck. This stationary part of the truck was generally a plate connecting the lower ends of the uprights or channels and would necessarily be of substantial thickness to absorb the thrust from the ram cylinder upon extension of the ram piston. The thickness of the plate receiving the lowermost ends of the ram cylinder would necessarily reduce the cylinder height for a particular truck and thus would proportionally decrease the height of the lift possible for the truck. The particular mounting of the instant invention does not require a plate or support memher for receiving the lowermost ends 43 of ram cylinder 42, thus permitting a ram cylinder length of the full 'height of the primary upright 10. In the particular embodiment disclosed, the ram cylinder 42 does not extend for the full length of the primary upright 10 as shown in FIGURE 4, but terminates at its end 43 adjacent bearing blocks 5.

As best seen in FIGURES 5 and 6, the secondary ram cylinders 42, for effecting uplifting of the mast uprights, are mounted in the side areas of the lift truck adjacent the primary or fixed upright. This novel mounting arrangement of the secondary ram cylinders of the present invention permits a more open line of sight vision for the operator in the central area of the lift truck over corresponding mounting arrangements in the lift truck prior art.

The upper end of secondary uprights 13 are interconnected by bracing member as seen in FIGURES 2 and 6. Bracing member 50 has a U-shaped configuration with side bearing portions 51 secured to the secondary uprights 13. When the uprights 13, 14 and 15 are in their lowermost or retracted position of FIGURE 1, the bearing portions 51 of bracing member 50 are positioned closely adjacent the upper end of secondary ram pistons 44. A pair of flexible members, such as link chains 55 are provided each of which are secured at their one end to the ram cylinder flange 41 at 54 and extend over a sheave 56 carried by the secondary upright 13 and are secured at their other end at anchor plate 57 secured to the lower portion of the third or tertiary upright 14 as seen in FIGURES 3 and 4. Another pair of flexible members as link chains 60 are provided having their one end secured by anchor means 61 attached to bracing member 50 and extending over sheave or roller 62 mounted on the third or tertiary section 14, with their other end being connected to anchor plate 63 secured to the lower portion of the quad or fourth upright 15 as seen in FIGURES 3 and 4.

With the assembly of the present invention as described hereinabove, it will now be apparent that upon the application of hydraulic fluid the secondary ram cylinder 42, the ram piston 44 will be raised upwardly directly engaging the bearing portion 51 of the bracing member 50 interconnecting the secondary uprights 13 thereby effecting upper movement of the secondary uprights upon extension of ram piston 44. Simultaneous with this movement of the secondary ram piston 44 and secondary upright 13, the tertiary or third upright 14 is also raised, the velocity-of this latter movement being substantially twice the speed of the aforesaid ram movement due to the reaving arrangement of the link chains 55 described hereinabove. Simultaneous with the beforedescribed movement of lthe secondary and tertiary uprights upon extension of the secondary ram piston 44, the quad or fourth mast is also raised, the velocity of this latter movement being subtantially three times the speed of the aforesaid movement of the piston ram 44 due to the reaving arrangement of the link chains 60 described hereinabove.

As best seen in FIGURE 2, the secondary ram 44 is approximately as long as; the mast sections of the assembly and through the above-described reaving arrangement is effective upon actuation to extend said assembly a distance equal to at least approximately three times the height of any one of said mast sections.

In prior art lift truck schemes of collapsible mast assemblies and hydraulic ram mountings, it is common for the ram piston to move a substantial distance before effecting any uplifting movement of the extendible mast sections. In the instant invention, however, the distance between the ram piston in its retracted position and the bearing portion of the secondary upright is an absolute minimum because of the novel mounting arrangement of the secondary ram; thus, a relatively short movement of the secondary ram pistons is necessary to effect uplifting movement of the extendible mast assembly.

Furthermore, because there is nothing more than a surface contact between the secondary ram pistons 44 and the bearing portions 51 integral with secondary uprights 13, the secondary uprights may weave or move relative to the ram pistons without affecting the operation of the ram pistons or the relation of the pistons to the secondary ram cylinders.

The primary and secondary rams 23 and 40 respectively, are each preferably of the single action type as referred to in the art, being actuated by hydraulic fluid to raise the load carriage 21 and the several mast sections 13, 14 and of the above-described assembly, the rams upon being drained of their actuating fluid permitting said elements to return gravitationally to their lowered and collapsed positions respectively, as illustrated in FIGURE 1. It is desirable to connect the primary and secondary rams 23 and 40 into a single hydraulic control circuit (not shown) which may be manually operable at the usual operator station on the lift truck, whereby hydraulic fluid is supplied simultaneously to each of said rams. In such an arrangement, the primary ram 23 is preferably larger in diameter than the secondary ram 40, whereby the primary ram is actuated at a somewhat lower hydraulic pressure than the secondary ram, it being intended that for any one mast assembly the primary ram 23 is actuable so as to raise the load carriage in the manner above described to its full free lift position prior to the secondary ram 40 being actuated to begin to raise some mast sections of said assembly.

It is also intended in the instant invention that upon permitting the hydraulic fluid to drain from the primary and secondary rams when the load carriage and mast sections are in their extended positions, the ram sizes are such that they permit the mast sections to move to their fully collapsed position of FIGURE 1 prior to the hydraulic pressure being lowered sufficiently in the primary ram 23 to initiate the lowering movement of the load carriage. As will be appreciated by those skilled in the art, it is possible to use primary and secondary rams of equal or of desired different sizes to control the sequence of movement for the respective load carriage and mast sections of the assembly. The instant mast assembly may be provided with conventional latching means to retain the mast sections in their collapsed position during the free lift movement of the load carriage and to retain the load carriagein its uppermost free lift position during collapsing of the mast section; such latch means for retaining the respective load carriage and mast sections in their desired positions being conventional and not forming a part of the instant invention are not described in detail herein.

The arrangement described hereinabove of anchoring one end of chain 55 to secondary ram'cylinder flange 41 is effective in reducing the stresses on flange 12 integral with primary uprights 10 during uplifting of the mast assembly. More particularly, chain link'55 is connected at its lower end to the secondary ram cylinder flange 14 which in turn is connected to the primary upright flange 12. With this mounting arrangement it is seen that primary upright flange member 12 and primary uprights 10 are loaded with a downward stress upon extension of the secondary ram pistons 44, which stress is at least partially offset by an upward stress from the pull of link chains 55 during upward movement of the sheave 56 upon extension of the secondary ram pistons 44. The offsetting of stresses permits a thinner flange plate 12 and smaller channel members 10 than normally would be necessary without the novel arrangement of the instant invention.

Having thus described in detail the preferred embodiment of the mast assembly incorporating the inventive concepts of the present invention herein, it Will be realized that the present invention is susceptible to various modifications, arrangements, and combinations of parts thereof without departing from the aforesaid concepts as are defined in the appended claims.

What is claimed is:

1. In an industrial truck, a lifting mast having fixed uprights and movable uprights mounted forwardly of said fixed uprights for movement relative to said fixed uprights, a lift ram for actuating said movable uprights, a flange member fixed to the upper end of said fixed uprights and extending rearwardly of said fixed uprights, the upper end of said ram being rigidly secured to and suspended from said fixed flange member, said movable uprights including secondary uprights mounted for movement on said fixed uprights, a bearing portion fixed to the upper end of said secondary uprights and extending in overlying relationship to said lift ram, said ram bearing against said bearing portion to actuate said secondary uprights.

2. An industrial truck as claimed in claim 1 in which said fixed uprights comprise a pair of vertically extending spaced uprights interconnected by said flange member and one ram is fixed to said flange member adjacent each spaced upright.

3. An industrial truck as claimed in claim 1, in which said movable uprights include tertiary uprights mounted for movement on secondary uprights and a flexible memher is fixed at one end to said flange member and at its other end to said tertiary uprights, a guide means for said flexible member mounted on said secondary uprights, the said flexible member applying a force to said flange member opposite in direction to the reaction force of said ram on said flange member.

4. An industrial truck as claimed in claim 2 in which said movable uprights include secondary uprights mounted for movement on said primary uprights and tertiary uprights movably mounted on said secondary uprights, a bearing portion fixed to the upper end of said secondary uprights and extending in overlying relationship to each 7 of said rams, said rams bearing against said bearing portion to actuate said secondary uprights.

5. An industrial truck as claimed in claim 2 in which said movable uprights include tertiary uprights mounted for movement on secondary uprights, a pair of flexible members are each fixed at one end to said flange member and at the other end to said tertiary uprights, a guide means for said flexible member mounted on said secondary uprights, the said flexible members applying a force to said flange member opposite in direction to the reaction force of each ram on said flange member.

6. An industrial truck as claimed in claim 3 in which said secondary upright has bearing portions overlapping said rams, said ram has a piston extending upwardly therefrom, the exposed end of the piston being spaced from said bearing portion when the ram is retracted but bearing directly against said bearing portion when the ram is protracted.

7. In an industrial truck as claimed in claim 3 in which a last upright having a load carriage mounted thereon is mounted on said tertiary uprights, said secondary and tertiary uprights each having guide means secured to the upper end and a flexible member passing over said guide means and having one end connected to the preceding upright and the other end connected to the next succeeding upright, whereby upon actuation of said rarn all of said movable uprights are moved longitudinally relative to each other. 5

References Cited UNITED STATES PATENTS 2,979,162 4/1961 Quayle 187'9 3,338,335 8/1967 McNeeley 187-9 2,250,321 7/1941 Aron 1878.43 2,581,791 1/1952 Gilman 187-9 2,582,999 1/1952 Lehmann 1879 2,877,868 3/1959 Gunning 1879 2,915,143 12/1959 Simmons 187--8.41 3,208,556 9/1965 Shaffer 187-9 FOREIGN PATENTS 659,933 3/1963 Canada.

EVON C. BLUNK, Primary Examiner.

H. C. HORNSBY, Assistant Examiner. 

